1. Field of the Invention
This invention deals with a novel process for the preparation of 2-hydroxy-4-(2'-hydroxyethoxy)benzophenones having a structure (FIG. I) ##STR1## wherein R.sup.1 and/or R.sup.2 may be hydrogen, hydroxyl, hydroxyethoxy, fluorine, chlorine, bromine, cyanide, C.sub.1 -C.sub.8 alkyl or alkoxy; a C.sub.4 -C.sub.7 cycloalkyl; a C.sub.1 -C.sub.4 alkyl substituted with one or more fluorine, chlorine or bromine atoms; or a phenoxy, benzyl, or phenyl substituted with fluorine, chlorine, bromine, a C.sub.1 -C.sub.4 alkyl, or a C.sub.1 -C.sub.4 alkoxy.
The process is carried out by reacting 2,4-dihydroxybenzophenones (FIG. II), ##STR2## for which R.sup.1 and R.sup.2 may be any of the substitutes described for FIG. I, with ethylene carbonate in the presence of a catalyst at elevated temperatures. The reaction product is subsequently isolated from the reaction mixture.
2. Description of the Prior Art
There are a number of publications which address the synthesis of the subject compound. Eggensperger discloses in U.S. Pat. No. 3,676,471, a method wherein 2-hydroxy-4-(2'-hydroxyethoxy)benzophenones may be prepared by ethoxylating 2,4-dihydroxybenzophenones with either ethylene oxide or with ethylene carbonate in the presence of basic catalysts, preferably alkali carbonates, alkali earth carbonates or alkali alkolates. This method however has a number of disadvantages. It requires the use of solvents, particularly ketones. Because of the basic nature of the reaction mixture only substantially inert ketones such as diisobutyl ketone may be employed. When ethylene carbonate is the alkoxylating agent, it must be used in large excess with a correspondingly high concentration of an auxiliary base. The above contributes significantly to the cost of the process. Further, Example 1 discloses that the reaction product is obtained by extraction with a chlorinated hydrocarbon. Halogenated hydrocarbons present problems because they are toxic and potential environmenal hazards.
U.S. Pat. Nos. 4,261,922 and 4,341,905 claim the use of potassium and/or general alkali metal halogen salts as catalysts used under neutral conditions to avoid side reactions.
U.S. Pat. No. 4,310,708, discloses the use of phosphonium salts as catalysts. The process also discloses a reaction exhibiting good selectivity, that may be carried out in an inert organic solvent, but preferably in the absence of said organic solvent. The use of phosphonium salts as a catalyst is undesirable because of the environmental hazard they pose.
The Bulletin of the Chemical Society of Japan, Vol. 46, 553-556 (1978), discloses the use of tetraethylammonium halogens as catalysts, but only with monofunctional phenols as reactants.